Intravenous versus oral iron for anaemia among pregnant women in Nigeria (IVON): an open-label, randomised controlled trial

Summary Background Oral iron for anaemia in pregnancy is often not well tolerated, with poor adherence. Iron administered intravenously might address these tolerance and adherence issues. We investigated the effectiveness and safety of intravenous ferric carboxymaltose versus oral ferrous sulphate on anaemia and iron deficiency among pregnant women in Nigeria. Methods We did a multicentre, open-label, parallel, randomised controlled trial of pregnant women (aged 15–49 years) with haemoglobin (Hb) concentrations of less than 10 g/dL at 20–32 weeks’ gestation from 11 primary, secondary, or tertiary health facilities in Nigeria (five in Lagos and six in Kano). Exclusion criteria included vaginal bleeding, blood transfusion or major surgery within the past 3 months, symptomatic anaemia, anaemia known to be unrelated to iron deficiency, clinically confirmed malabsorption syndrome, previous hypersensitivity to any form of iron, pre-existing maternal depression or other major psychiatric illness, immune-related diseases, such as systemic lupus erythematosus or rheumatoid arthritis, or severe allergic reactions. Participants were randomly assigned (1:1) by nurses and doctors using a web-based randomisation service to either receive a single dose of intravenous ferric carboxymaltose (20 mg/kg to a maximum of 1000 mg) or oral ferrous sulphate (200 mg; 65 mg elemental iron) three times daily until 6 weeks postpartum. The study was primarily unmasked. Primary outcomes were maternal anaemia (Hb <11 g/dL) at 36 weeks’ gestation and preterm birth at before 37 weeks’ gestation, with analysis by intention to treat in participants with available data. This study was registered at the ISRCTN registry on Dec 10, 2020 (ISRCTN63484804) and on ClinicalTrials.gov (NCT04976179) on April 7, 2021. Findings Between Aug 10, 2021, and Dec 15, 2022, 13 724 pregnant women were screened for eligibility. 12 668 were excluded due to ineligibility for inclusion, and 1056 provided consent to participate and were randomly assigned to either the intravenous or oral administration groups. 527 were assigned to the intravenous ferric carboxymaltose group and 529 were assigned to the oral ferrous sulphate group. 518 in the intravenous group were assessed at 36 weeks’ gestational age and after 518 deliveries, and 511 completed the 6 weeks postpartum visit. 513 in the oral ferrous sulphate group were assessed at 36 weeks’ gestational age and after 512 deliveries, and 501 completed the 6 weeks postpartum visit. No significant difference was found in anaemia at 36 weeks (299 [58%] of 517 in the intravenous group vs 305 [61%] of 503 in the oral group; risk ratio 0·95, 95% CI 0·85–1·06; p=0·36), nor in preterm birth (73 [14%] of 518 vs 77 [15%] of 513; 0·94, 0·70–1·26; p=0·66). There were no significant differences in adverse events. The most common adverse events were diarrhoea (in six participants) and vomiting (in three participants) in the oral group and fatigue (in two participants) and headache (in two participants) in the intravenous group. Interpretation Although the effect on overall anaemia did not differ, intravenous iron reduced the prevalence of iron deficiency to a greater extent than oral iron and was considered to be safe. We recommend that intravenous iron be considered for anaemic pregnant women in Nigeria and similar settings. Funding Bill & Melinda Gates Foundation.

Intravenous iron requires minimal patient-facility contact and corrects anaemia much faster than oral preparations.Recent intravenous iron preparations have been found to be well tolerated and with fewer adverse effects than the previously available high molecular weight iron dextrans.
In the Nigerian setting, pregnant women seek antenatal care late, and have poor ANC clinic attendance.Thus, the use of a minimally dosed iron formulation that is safe, rapidly effective, and cost-effective can improve the likelihood of prompt and appropriate IDA treatment and potentially reduce the risk of complications.
Prior evidence has not shown oral iron to be impactful for important clinical outcomes such as low birthweight, preterm delivery; thus, intravenous iron may be more effective in this regard.Findings from this study could potentially protect significant proportions of pregnant women and neonates in LMICs from severe morbidity and mortality.

Scope of the analyses
These analyses will assess the effectiveness and safety of intravenous ferric carboxymaltose in comparison to oral ferrous sulphate (control) to treat iron deficiency anaemia (IDA) and will be included in the clinical study report.

Study Objectives
To determine the comparative effectiveness of intravenous ferric carboxymaltose (intervention) versus oral ferrous sulphate (control) for treating iron deficiency anaemia in pregnancy and to compare the tolerability, safety, and the cost-effectiveness of intravenous versus oral iron among pregnant Nigerian women with moderate and severe IDA at 20-32 weeks' gestation.
Specific objectives include: 1.To determine the effect of intravenous ferric carboxymaltose on the prevalence of maternal anaemia at 36 weeks' gestation and on the increase in haemoglobin concentration 4 weeks after administration compared with oral ferrous sulphate in pregnant women with iron deficiency anemia.2. To determine the effect of intravenous ferric carboxymaltose on the incidence of postpartum haemorrhage, sepsis, shock, the need for blood transfusion, the prevalence of depression and other maternal clinical outcomes, compared with oral ferrous sulphate in pregnant women with iron deficiency anaemia.3. To determine the effect of intravenous ferric carboxymaltose on the incidence of low infant birthweight, prematurity, stillbirth, and neonatal mortality, and on breastfeeding and immunization, compared with the use of oral ferrous sulphate in pregnant women with iron deficiency anaemia.4. To measure implementation outcomes of intravenous ferric carboxymaltose including its acceptability, feasibility, and fidelity in the context in which the trial is being carried out. 5. To determine the cost-effectiveness of intravenous ferric carboxymaltose compared with oral ferrous sulphate in the treatment of iron deficiency anaemia in pregnancy.

Endpoints
Primary 1. Prevalence of maternal anaemia at 36 weeks The prevalence of maternal anaemia is defined as haemoglobin <10g/dL at 36 weeks.
Haemoglobin measurement nearest to 36 + 0 weeks of gestation will be used, of all the tests between 30 weeks and delivery.Analysis will be by intention to treat, using log-binomial models that allow the estimation of risk ratios, 95% confidence intervals and two-tailed pvalues.No covariate adjustment will be considered.Missing values will be ignored.

Incidence of preterm birth
Preterm births will be defined as births before 37 + 0 weeks gestation using the agreed gestational age at trial entry.Analysis will be by intention to treat, using log-binomial models that allow the estimation of risk ratios, 95% confidence intervals and two-tailed p-values.No covariate adjustment will be considered.Missing values will be ignored.

Hypothesis:
1. We expect a 14% lower prevalence of anaemia at 36 weeks' gestation in the ferric carboxymaltose (intervention) group compared to the ferrous sulphate (control) group.
2. There will be a lower incidence of preterm birth among the intervention group, compared with the control group.Secondary 1. Increase in maternal haemoglobin levels at 4 weeks post-initiation of treatment.In some cases, samples included in the 36-week primary endpoint analysis will also be included here if they meet both criteria.
2. The safety and tolerability of intravenous ferric carboxymaltose versus oral ferrous sulphate, including the incidence of hypophosphatemia and severity of maternal adverse effects.
3. Severe maternal events, specifically, postpartum haemorrhage, sepsis, shock, and the need for blood transfusion.Depression will be defined as EPDS score >10 any time after birth.Given the EPDS is assessed multiple times, the highest score will be used.Any woman who commits or attempts suicide will be regarded as depressed, regardless of her score.Any woman who self-reports depressive illness or whose family member or physician reports a depressive illness will also be regarded as depressed.
Analysis will be by intention to treat, using log-binomial models that allow the estimation of risk ratios, 95% confidence intervals and two-tailed p-values.No covariate adjustment will be considered.Missing values will be ignored.
3 Study Methods

General Study Design and Plan
Multicenter, parallel, open label individually randomized controlled trial, with 1,056 women allocated in a 1:1 ratio in conjunction with a cost-effectiveness analysis.
Participants will be seen in clinic every 4 weeks till 28 weeks' gestation and every 2 weeks until 36 weeks, then weekly until delivery.

Inclusion-Exclusion Criteria and General Study Population
Inclusion criteria: ▪ Pregnant women aged 15 to 49 years old between 20*-and 32**-weeks' gestational age o 20 weeks was chosen as lower limit because Nigerian women register for ANC care in the second trimester, typically at 20 weeks or later.o 32 weeks as the upper limit to enable assessment of impact of both intervention and standard of care on perinatal events by evaluating their haemoglobin concentration by 36 weeks.▪ Baseline (enrollment) laboratory-confirmed moderate or severe anaemia (Hb < 10g/dl).

Exclusion criteria:
▪ Medically confirmed significant bleeding, major surgery or received blood transfusion within the last 3 months.▪ Severe symptomatic anaemia needing urgent correction with blood transfusion.▪ Anaemia of other known causes besides IDA e.g., sickle cell anaemia, thalassemia, autoimmune diseases, chronic kidney disease, cancer, human immunodeficiency virus infection (HIV).▪ Clinically confirmed malabsorption syndrome ▪ Hypersensitivity to any form of iron treatment.▪ History of any immune related illness e.g., SLE, Rheumatoid arthritis ▪ Preexisting maternal depression or other psychiatric illness ▪ Severe allergic reactions such as severe asthma ▪ History of known drug allergy

Randomization and Blinding
At the enrolment visit, a pregnant woman who is found to have AIP through haemoglobin testing, using the Hemocue® haemoglobinometer, with a haemoglobin concentration of 9.9g/dL or lower, who meets the eligibility criteria and gives informed consent will be enrolled.Eligible participants will be consecutively enrolled.They will be randomized to one of the two treatments groups.Individual randomization and allocation concealment will be done with the use of a web-based randomization software known as 'Sealed envelope' in a 1:1 ratio in blocks stratified according to center

Analysis Time Windows
We will allow the inclusion of variables collected around the following time windows.

Description of variables
The key variables used for analysis are described below;
▪ A secondary endpoint Small for gestational age (SGA) Binary variable (0,1).Calculated from the birthweight and gestational age based on the Oken thresholds (1).

EPDS score
Continuous variable.

Depression
Binary variable (0,1).Calculated from the EPDS score.Depression will be defined as EPDS score >10 any time after birth.Given the EPDS is assessed multiple times, the highest score will be used.Any woman who commits or attempts suicide will be regarded as depressed, regardless of her score.Any woman who self-reports depressive illness or whose family member or physician reports a depressive illness will also be regarded as depressed.

Sample Size
At the 5% significance and precision level, 1,056 pregnant women (528 in each study arm) are required to detect a difference in improvement in the prevalence of AIP at term by 14%, between the control group (70% corrected) and the intervention group (84% corrected), as seen in a multicountry international study in Europe, Asia and Australia(2) at 90% power, adjusting for 15% attrition and protocol violations(3).
To assess the outcome of increase in haemoglobin concentration: At the 5% significance level, 990 pregnant women (495 in each study arm) are required to detect a difference in improvement in the Hb level after 4 weeks among anaemic pregnant women at term by 1g/l, between the control group and the intervention group, at 90% power, adjusting for a 15% attrition and protocol violations, giving a superiority and two-tailed tests of hypotheses (3).A systematic review reported a pooled confidence interval of mean difference of haemoglobin between treatment and control arm as 3.9 to +10.9 g/L(4) while Kochhar et al. in India( 5) reported a difference in mean haemoglobin of 2g/dl.We therefore assumed a conservative clinically relevant effect size of 1g/dl to achieve the current sample size.
There was no previous study in our environment describing the efficacy of intravenous iron administration on the outcome of preterm deliveries among pregnant women with anaemia.Prevalence of preterm birth in Nigeria is between 16.8% and 32.9% (6)(7)(8).According to a systematic review, there was about 1.6-fold risk of preterm delivery among anaemic mothers.(RR: 1.56, 95%CI: 1.25 -1.95) (9).Thus, the prevalence of preterm delivery among anaemic mothers is assumed to be between 28.9% and 52.6%.To assess the secondary outcome of prevalence of low birth weight: At the 5% significance level, 892 pregnant women (446 in each study arm) are required to detect a 20% decrease (as shown from prenatal iron use) (10) in the prevalence of low birth weight from 15% (average in Nigeria) to 12%, at the 5% significance level with 90% power, adjusting for a 15% attrition and protocol violations.
For depression, using a 13% incidence of post-partum depression (PPD) among non-anemic patients, a sample size of 294 pregnant women (147 women per arm) would detect a 2.8-fold increase in PPD (37%) or higher in the defined anemic group (hemoglobin < 110) (11), with a statistical power of 90% and a 5% significance level, while adjusting for a 15% attrition rate.
A total of 1056 pregnant women with GA between 20 and 32 weeks will be enrolled into the IVON study.

Timing of Analyses
The final analysis will be performed on the final unblinded dataset, after data cleaning is completed and database is locked.

Intention to Treat (ITT) population
▪ The intention to treat population refers to all subjects who were randomized.Following the intention-to-treat principle, patients will be analyzed according to the treatment they were assigned to at randomization.

Modified Intention to Treat (mITT) population
▪ All ITT patients that completed 36 weeks or delivery will be eligible for assessment of the primary endpoint.This population will be considered in exploratory analysis.

Per protocol population
▪ A per protocol population will not be considered in the analysis

Covariates and Subgroups
Continuous variables will be summarized using the following descriptive statistics, n (non-missing sample size), mean, standard deviation (SD), medians, minimum and maximum.The frequency and percentages (based on the non-missing sample size) of observed levels will be reported for all categorical measures.In general, all summary tables will be structured with a column for the overall population and sorted by region.Summary tables will also be presented for each treatment, and will be annotated with the total population size relevant to that table/treatment.The number of missing observations will be presented in the footnote of each table.

Subject Disposition
The following CRFs will be used to determine which participants reached the following stages.

Visit (target day) CRF
Baseline (0) Enrolment form The time-dependent rates of recruitment will be provided in graphical format.

Delivery
A flow diagram of participant selection will be provided as below to provide an explicit statement of the key statistics of the study.Binary variable (0, 1).Blood loss postpartum > 1,000 ml based on visual or weight method, whichever is greater (16).Neonatal mortality Binary variable (0, 1).Defined as infant age at death <42 days ▪ A secondary endpoint Vaccination up-todate Binary (0,1) at 1, 2 and 4 weeks.Calculated from BCG, oral polio and hepatitis vaccination.
▪ A secondary endpoint Small for Binary variable (0,1).Calculated from the birthweight and gestational age.
linear mixed regression models will be used, and the beta coefficients exponentiated (17).Relevant measures of uncertainty (confidence intervals and p-values) will be reported.In addition, logbinomial regression models with and without statistical control for region and facility type will be estimated and compared with the log-binomial GLMM model.The final model will be selected using the Akaike Information Criterion (AIC).In some cases, the log-binomial models may not converge and log-Poisson models, which provide consistent but not fully efficient estimates of the relative risk, and its confidence intervals will be used (18).Results will be presented in figures.

Co-primary Efficacy Analysis -preterm birth
The main analysis will be conducted in the ITT population.
The incidence of preterm births will be presented as N and percent of the total study population, by region, and by treatment group (IV iron vs. oral iron). Hypothesis: 1.There will be a lower incidence of preterm birth among the intervention group, compared with the control group.
Log-binomial regression models will be used, and risk ratios and confidence intervals presented.
To obtain the relative risk of preterm birth accounting for region and facility type, logistic generalized linear mixed regression models will be used, and the beta coefficients exponentiated (17).Relevant measures of uncertainty (confidence intervals and p-values) will be reported.In addition, log-binomial regression models with and without statistical control for region and facility type will be estimated and compared with the log-binomial GLMM model.The final model will be selected using the Akaike Information Criterion (AIC).In some cases, the log-binomial models may not converge and log-Poisson models, which provide consistent but not fully efficient estimates of the relative risk, and its confidence intervals will be used (18).Results will be presented in figures.

Secondary Analyses of Primary Endpoints
The mITT population will be used for analysis.The maternal anaemia and preterm birth analyses will be repeated and findings compared to the primary analyses.

Analyses of Important Secondary Endpoint -maternal depression
This analysis will be conducted in the ITT populations.
The EPDS score will summarized as a continuous outcome using N, mean, standard deviation (SD), median, minimum and maximum, overall and by treatment group, at baseline and 36 weeks.The proportion of participants that attain the minimally important change of four points will be estimated and compared by treatment group (19).
The frequency of occurrence of maternal depression will be presented as N and percent of the total study population, by region, and by treatment group (IV iron vs. oral iron).
To obtain the relative risk and 95% CI of maternal depression, as well as the relative risk of achieving the minimally important change, log-binomial regression models will be used.In some cases, the logbinomial models may not converge and log-Poisson models, which provide consistent but not fully efficient estimates of the relative risk, and its confidence intervals will be used (18).

Analyses of Secondary Endpoints
This analysis will be conducted in both the ITT and mITT populations.
The frequency of occurrence of the categorical endpoints will be presented as N and percent of the total study population, by region, and by treatment group (IV iron vs. oral iron).N, mean, standard deviation (SD), median, minimum and maximum will summarize continuous variables.
To obtain the relative risk and 95% CI of the occurrence of the primary and secondary endpoints, log-binomial regression models will be used.In some cases, the log-binomial models may not converge and log-Poisson models, which provide consistent but not fully efficient estimates of the relative risk, and its confidence intervals will be used (18).Results will be presented in tables and figures.

Subgroup analyses
The ITT population will be used for analysis.The outcomes of interest will be the primary and secondary endpoints.The analyses will be conducted among those with iron deficiency anaemia at enrolment compared to those without.
Continuous endpoints will summarized using N, mean, and standard deviation (SD), in the overall IDA (vs.non-IDA population) and by treatment group, at 36 weeks.Linear regression models will be used to obtain mean difference and 95% CI in each subgroup.
The frequency of occurrence of the dichotomous endpoints will be presented as N and percent of the IDA (vs.non-IDA) population, and by treatment group (IV iron vs. oral iron).
To obtain the relative risk and 95% CI of each dichotomous endpoint, log-binomial regression models will be used.In some cases, the log-binomial models may not converge and log-Poisson models, which provide consistent but not fully efficient estimates of the relative risk, and its confidence intervals will be used (18).Likelihood ratio tests will be used to compare models with an interaction term for IDA status and treatment to those without.
8 Safety Analyses

Extent of Exposure
We will examine the time to occurrence of any serious adverse events that occur in >5% of individuals who receive either intervention.This will be presented using median time to event as well as graphically with Kaplan-Meier curves.

Rationale for Adjustments of Statistical Analysis Plan from Protocol
Any changes from the protocol-specified definitions of aims, outcomes and statistical analytic approaches will be outlined below.These represent changes made prior to the database lock and unblinding of the study.a) Subgroup analysis based on iron deficiency anaemia was included.
-Earlier versions of the protocol had prespecified this analysis, which was omitted in error from the final version.b) Iron deficiency analysis at 36 weeks was added as a secondary endpoint -This endpoint was included to improve the evaluation of hematologic outcomes in the study c) Instead of evaluating the prevalence of vaccination with each of BCG, OPV and HBV, the secondary endpoint was changed to whether vaccination was up-to-date for baby's age.d) Breastfeeding timepoints for assessment were reduced to 2 and 6 weeks to align with study visits.e) The threshold for defining anaemia was changed from 11 g/dL to 10 g/dL which is in the published protocol.

Figure .
Figure.Flow diagram

Table SM3 Table SM3 .
Schedule of assessments

Table SM4 Table SM3 .
Differences in participants' characteristics by state

Table SM5 Table SM4 .
Incidence of hypophosphataemia during by treatment arm (N=1,056)RR -risk ratio.MD -mean difference.IV -intravenous.Hypophosphataemia refers to phosphate levels < 0.8075 mmol/l in maternal blood for the first 4 time points and phosphate level <1.4mmol/l for cord blood.

Table of Contents
prematurity (<37 weeks' gestation as dated from the last menstrual period or early ultrasound scan done not later than 22 weeks gestational age if unsure of LMP) (25) 4. The incidence of a. low infant birthweight (<2.5 kg), b.7.Incidence of depression linked to emotional well-being of mothers using the validatedEdinburgh Postnatal Depression Scale (EPDS).

Table 2 .
Analysis Time Windows

Table 3 .
Description of variablesContinuous variable, measured in weeks.The lower limit of acceptable range is 20 weeks.The usual upper limit is 44 weeks, beyond which baby is unlikely to have survived.
Hence, we utilized the power calculator in Stata version 17 statistical software (StataCorp.2021.Stata Statistical Software: Release 17. College Station, TX: StataCorp LLC) (40) to calculate the minimum sample size to be 892 women (446 per arm) based on the assumption that prevalence of preterm deliveries among anaemic pregnant women was 28.9%, given 90% power, a protective relative risk of intravenous iron against preterm delivery of 0.65 and a 20% loss to follow -up.
Anemia and preterm birth are primary endpoints that are derived variables.A number of secondary endpoints are also derived variables.Their definitions are provided in the table below.